
:root {
    --primary-color: #2c3e50;
    --secondary-color: #2980b9;
    --dark-color: #2c3e50;
    --light-color: #ecf0f1;
    --text-color: #34495e;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--light-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.navbar {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
}

.nav-links a {
    color: white;
    text-decoration: none;
    margin-left: 1.5rem;
    transition: opacity 0.3s;
}

.nav-links a:hover {
    opacity: 0.8;
}

.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 4rem 2rem;
    text-align: center;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.hero p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto 2rem;
}

.features {
    padding: 4rem 2rem;
    max-width: 1500px;
    margin: 0 auto;
    width: 100%;
}

.section-title {
    text-align: center;
    margin-bottom: 3rem;
    color: var(--dark-color);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr); /* 明确设置为3列 */
    gap: 2rem;
    justify-content: center;
}

.feature-card {
    background-color: white;
    border-radius: 10px;
    padding: 2rem;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: transform 0.3s;
    width: 100%; /* 确保卡片宽度填满网格单元格 */
}

.feature-card:hover {
    transform: translateY(-10px);
}

.feature-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 1rem;
    color: var(--dark-color);
}

.exam-types {
    background-color: white;
    color: var(--dark-color);
    padding: 4rem 2rem;
    text-align: center;
    margin-top: auto;
}

.exam-cards {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 2rem;
    margin-top: 3rem;
}

.exam-card {
    background-color: var(--light-color);
    color: var(--dark-color);
    border-radius: 10px;
    padding: 2rem;
    width: 250px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: all 0.3s ease;
}

.exam-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.exam-card h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}


.start-btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 1rem 2.5rem;
    border-radius: 50px;
    cursor: pointer;
    margin-top: 2rem;
    font-size: 1.2rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}

.start-btn:hover {
    background-color: var(--secondary-color);
    transform: translateY(-3px);
    box-shadow: 0 6px 15px rgba(0,0,0,0.3);
}

footer {
    background-color: var(--dark-color);
    color: white;
    text-align: center;
    padding: 2rem;
}

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .exam-cards {
        flex-direction: column;
        align-items: center;
    }

    .exam-card {
        width: 100%;
        max-width: 350px;
    }
}